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Fix handling of NaN values in BRIN minmax multi

author Tomas Vondra <tomas.vondra@postgresql.org>

Sat, 6 Nov 2021 00:25:31 +0000 (01:25 +0100)

committer Tomas Vondra <tomas.vondra@postgresql.org>

Sat, 6 Nov 2021 00:50:44 +0000 (01:50 +0100)

When calculating distance between float4/float8 values, we need to be a
bit more careful about NaN values in order not to trigger assert. We
consider NaN values to be equal (distace 0.0) and in infinite distance
from all other values.

On builds without asserts, this issue is mostly harmless - the ranges
may be merged in less efficient order, but the index is still correct.

Per report from Andreas Seltenreich. Backpatch to 14, where this new
BRIN opclass was introduced.

Reported-by: Andreas Seltenreich
Discussion: https://postgr.es/m/87r1bw9ukm.fsf@credativ.de

src/backend/access/brin/brin_minmax_multi.c patch | blob | blame | history

src/test/regress/expected/brin_multi.out patch | blob | blame | history

src/test/regress/sql/brin_multi.sql patch | blob | blame | history

diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c

index ee6c4795f1c0d6482f64558837f7dc8130dd60fb..a85dfdfec45c62f99cd05ba563f7681ac70ec6aa 100644 (file)

--- a/src/backend/access/brin/brin_minmax_multi.c

+++ b/src/backend/access/brin/brin_minmax_multi.c

@@ -73,6 +73,7 @@

#include "utils/builtins.h"

#include "utils/date.h"

#include "utils/datum.h"

+#include "utils/float.h"

#include "utils/inet.h"

#include "utils/lsyscache.h"

#include "utils/memutils.h"

@@ -1872,6 +1873,14 @@ brin_minmax_multi_distance_float4(PG_FUNCTION_ARGS)

float a1 = PG_GETARG_FLOAT4(0);

float a2 = PG_GETARG_FLOAT4(1);

+ /* if both values are NaN, then we consider them the same */

+ if (isnan(a1) && isnan(a2))

+ PG_RETURN_FLOAT8(0.0);

+ /* if one value is NaN, use infinite distance */

+ if (isnan(a1) || isnan(a2))

+ PG_RETURN_FLOAT8(get_float8_infinity());

* We know the values are range boundaries, but the range may be collapsed

* (i.e. single points), with equal values.

@@ -1890,6 +1899,14 @@ brin_minmax_multi_distance_float8(PG_FUNCTION_ARGS)

double a1 = PG_GETARG_FLOAT8(0);

double a2 = PG_GETARG_FLOAT8(1);

+ /* if both values are NaN, then we consider them the same */

+ if (isnan(a1) && isnan(a2))

+ PG_RETURN_FLOAT8(0.0);

+ /* if one value is NaN, use infinite distance */

+ if (isnan(a1) || isnan(a2))

+ PG_RETURN_FLOAT8(get_float8_infinity());

* We know the values are range boundaries, but the range may be collapsed

* (i.e. single points), with equal values.

diff --git a/src/test/regress/expected/brin_multi.out b/src/test/regress/expected/brin_multi.out

index d3d693e4649427b270828bfa47ea707a0615f1a0..f3309f433f878a3a768065d21629068cd35147be 100644 (file)

--- a/src/test/regress/expected/brin_multi.out

+++ b/src/test/regress/expected/brin_multi.out

@@ -347,6 +347,9 @@ SELECT brin_desummarize_range('brinidx_multi', 0);

(1 row)

VACUUM brintest_multi; -- force a summarization cycle in brinidx

+-- Try inserting a values with NaN, to test distance calculation.

+insert into public.brintest_multi (float4col) values (real 'nan');

+insert into public.brintest_multi (float8col) values (real 'nan');

UPDATE brintest_multi SET int8col = int8col * int4col;

-- Tests for brin_summarize_new_values

SELECT brin_summarize_new_values('brintest_multi'); -- error, not an index

diff --git a/src/test/regress/sql/brin_multi.sql b/src/test/regress/sql/brin_multi.sql

index 70b751068b06bf84a41a97448638c7bbcecb96d2..2189b6ccf4234af1d28299da407225c23505d03f 100644 (file)

--- a/src/test/regress/sql/brin_multi.sql

+++ b/src/test/regress/sql/brin_multi.sql

@@ -351,6 +351,10 @@ FROM tenk1 ORDER BY unique2 LIMIT 5 OFFSET 5;

SELECT brin_desummarize_range('brinidx_multi', 0);